Products > Test Equipment

My poor mans SMU - The Agilent 66311B

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nctnico:
Feet can be bought from Ebay for less money then Keysight is asking. Isn't there some generic knob which will fit?

SKPang:
I've ordered the knob from Keysight UK. £2.16 + VAT with free delivery.

Paid by credit card and thats it. No minimum order. Should be here this week.

ve7xen:

--- Quote from: macboy on February 28, 2016, 08:18:03 pm ---
--- Quote from: ve7xen on February 28, 2016, 05:58:23 am ---So I've done some additional testing/calibration, and my box does great as a power supply, well within spec per the verification procedure after calibration. However the current sink seems to have failed short. Though this would seem to short across the output rails, so perhaps it is part of the control circuitry for the 'downprogrammer' that's the problem.

In trying to track this down I'm finding this is by far the worst piece of HP test equipment to work on I've ever seen. All the component designators are hidden under the components, many of the test points called out in the service manual are unreachable with normal probes, and no schematic or component placement diagram seems to be available. It looks like I'm going to have to remove the A1 board to do further testing, which is also a much more arduous chore than most HP gear.

Ah well, at least it makes a great power supply if nothing else.

--- End quote ---
Keep in mind that while it can sink current, it is not programmable. The current sink will be around 1 to 2.5 A (depending on voltage at output terminals), regardless of programmed current limit.

--- End quote ---

Thanks I will look into this when I return home next week. From my reading of the verification procedure it seemed that it was programmable, and the block diagram does seem to show a constant current loop around the downprogramming regulator, so I'm not so sure that's the case, but you're probably right. I was seeing the 66311B put my 3.5A power supply into CC mode at 3.5A, while the display on the 66311B would show the setpoint on the current readback, which seemed a bit weird to me.

@stuartk Not willing to coordinate, but if you are I'm in for a couple of items ;).

macboy:

--- Quote from: ve7xen on February 29, 2016, 04:31:45 pm ---
--- Quote from: macboy on February 28, 2016, 08:18:03 pm ---
--- Quote from: ve7xen on February 28, 2016, 05:58:23 am ---So I've done some additional testing/calibration, and my box does great as a power supply, well within spec per the verification procedure after calibration. However the current sink seems to have failed short. Though this would seem to short across the output rails, so perhaps it is part of the control circuitry for the 'downprogrammer' that's the problem.

In trying to track this down I'm finding this is by far the worst piece of HP test equipment to work on I've ever seen. All the component designators are hidden under the components, many of the test points called out in the service manual are unreachable with normal probes, and no schematic or component placement diagram seems to be available. It looks like I'm going to have to remove the A1 board to do further testing, which is also a much more arduous chore than most HP gear.

Ah well, at least it makes a great power supply if nothing else.

--- End quote ---
Keep in mind that while it can sink current, it is not programmable. The current sink will be around 1 to 2.5 A (depending on voltage at output terminals), regardless of programmed current limit.

--- End quote ---

Thanks I will look into this when I return home next week. From my reading of the verification procedure it seemed that it was programmable, and the block diagram does seem to show a constant current loop around the downprogramming regulator, so I'm not so sure that's the case, but you're probably right. I was seeing the 66311B put my 3.5A power supply into CC mode at 3.5A, while the display on the 66311B would show the setpoint on the current readback, which seemed a bit weird to me.
...

--- End quote ---
I'm looking at the user manual, "USER’S GUIDE Agilent Model 66111A Fast Transient DC Source Agilent Model 66311B/D, 66309B/D Mobile Communications DC Source", Agilent Part No. 5964-8125, Page 144 "Supplemental Characteristics". The note given for the sink current states:

--- Quote ---1 The sink current decreases linearly from 2.8A @ 0 V to 1.2 A @ 15 V. Sink current does not track the programmed current.
--- End quote ---
Also on page 26,

--- Quote ---Figure 2-1 also shows a single range ? two quadrant capability. This means that the dc source is capable
of sourcing as well as sinking current over the output voltage range from zero volts to the rated voltage.
This negative current sinking capability provides fast downprogramming of the output of the dc source. It
can also be used to sink current from a battery charger, thus providing battery charger test capability. The
negative current is not programmable, and varies linearly from approximately 1.2 amperes at the full
rated voltage, to approximately 2.8 amperes at zero output voltage.".

--- End quote ---
This really is too bad.

mtdoc:
It is too bad about the lack of programmable current sinking.

Yesterday I replaced the loud fan with a quiet Vantec temp controlled fan. Much better!

I also ordered the Phoenix connector from Digikey. I think I'll hold off on front terminals.

I noticed NI makes a driver for this unit.  I wonder if anyone has developed a LabView VI for this?  The Keysight software looks nice but just way too expensive.

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